compiler, runtime: More steps toward separating int and intgo.

gcc/go/gofrontend/expressions.cc

gcc/go/gofrontend/gogo-tree.cc

gcc/go/gofrontend/gogo.h

gcc/go/gofrontend/runtime.cc

gcc/go/gofrontend/runtime.def

gcc/go/gofrontend/types.cc

libgo/go/bytes/indexbyte.c

libgo/go/syscall/signame.c

libgo/runtime/array.h

libgo/runtime/go-append.c

libgo/runtime/go-assert-interface.c

libgo/runtime/go-byte-array-to-string.c

libgo/runtime/go-caller.c

libgo/runtime/go-callers.c

libgo/runtime/go-can-convert-interface.c

libgo/runtime/go-cgo.c

libgo/runtime/go-check-interface.c

libgo/runtime/go-construct-map.c

libgo/runtime/go-convert-interface.c

libgo/runtime/go-eface-compare.c